For higher-energy photons, kerma is larger than absorbed dose because some highly energetic secondary electrons and X-rays escape the region of interest before depositing their energy.
32.
National standards laboratories such as the NPL provide calibration factors for ionization chambers and other measurement devices to convert from the instrument's readout to absorbed dose.
33.
For instance, the effective dose to the torso from a CT scan of the chest is about 5 mSv, and the absorbed dose is about 14 mGy.
34.
When measuring dose absorbed in a human due to exposure, units of absorbed dose are used ( the SI unit, the " rem " ), are used.
35.
"' Tissue-to-air ratio "'( TAR ) is a term used in radiotherapy treatment planning to help calculate absorbed dose to water in conditions other than those directly measured.
36.
The plasma half-life or " half life of elimination " is the time required to eliminate 50 % of the absorbed dose of a drug from an organism.
37.
Other significant areas are medical dosimetry, where the required treatment absorbed dose and any collateral absorbed dose is monitored, and in environmental dosimetry, such as radon monitoring in buildings.
38.
To avoid any risk of confusion between the absorbed dose and the equivalent dose, the absorbed dose is stated in grays and the equivalent dose is stated in sieverts.
39.
To avoid any risk of confusion between the absorbed dose and the equivalent dose, the absorbed dose is stated in grays and the equivalent dose is stated in sieverts.
40.
Other significant areas are medical dosimetry, where the required treatment absorbed dose and any collateral absorbed dose is monitored, and in environmental dosimetry, such as radon monitoring in buildings.
